Deep Dive: G5A06
The correct answer is A: As the frequency of the applied AC increases, the reactance decreases. How a capacitor reacts to AC is that as the frequency of the applied AC increases, the reactance decreases. Capacitive reactance XC = 1/(2πfC), so it's inversely proportional to frequency. For amateur radio operators, this is a fundamental relationship. Understanding this helps when working with capacitors.
Why Other Answers Are Wrong
Option B: Incorrect. Capacitive reactance doesn't increase with frequency - it decreases. XC = 1/(2πfC), so higher frequency means lower reactance. Option C: Incorrect. Reactance doesn't depend on amplitude - it depends on frequency and capacitance. Amplitude doesn't affect reactance. Option D: Incorrect. Reactance doesn't decrease with amplitude - it doesn't depend on amplitude at all. Amplitude doesn't affect reactance.
Exam Tip
Capacitor reactance = decreases with frequency. Think 'C'apacitor 'R'eactance = 'C'ontrary (decreases) with frequency. XC = 1/(2πfC), so reactance is inversely proportional to frequency. Not increases, not amplitude-dependent - just decreases with frequency.
Memory Aid
Capacitor reactance = decreases with frequency. Think 'C'apacitor 'R'eactance = 'C'ontrary (decreases). XC = 1/(2πfC), so reactance is inversely proportional to frequency. Higher frequency = lower reactance.
Real-World Example
A capacitor with 100 pF capacitance. At 1 MHz, reactance is about 1,590 ohms. At 10 MHz, reactance is about 159 ohms. As frequency increases, capacitive reactance decreases inversely. This is why capacitors pass high frequencies (low reactance).
Source & Coverage
Question Pool: 2023-2027 Question Pool
Subelement: G5A
Reference: 2023-2027 Question Pool · G5 - Electrical Principles
Key Concepts
Verified Content
Question from the official FCC General Class pool. Explanation reviewed by licensed amateur radio operators and mapped to the G5A topic.